Indication device and article incorporating same

ABSTRACT

A disc or like article ( 10, 115, 119 ) rotatable by drive means, such as a compact disc for use with a computer, includes indication means ( 12, 110, 120 ) which, when the disc is rotated at or above a predetermined angular velocity, provide an indication that rotation has occurred, which indication can be important if the disc contains confidential information. The indication device can be a tube formed with two enclosures separated by a breakable membrane ( 15, 16, 112, 122 ), a colored liquid/gel ( 17, 111 121 ) being in one enclosure and passing into the second enclosure, by breaking the membrane, when the disc is spun, thereby providing a visual indication thereafter of the spinning having occurred The invention also relates to such an indication means, per se, for after-fitting to a disc recorded on by spinning, and to a method of producing a disc with said indication means.

This invention relates to an indication device and also to an articleincorporating same, and has particular application to compact discs.Hereinafter, a disc or the like article will be referred to forconvenience as ‘a disc’.

Compact discs, particularly those used in the computer industry, oftencontain confidential information. Presently there is no means of tellingmerely from looking at such a compact disc whether the informationthereon has been retrieved i.e. whether the disc has been rotated on adisc drive.

An object of the invention is to address this problem.

According to a first aspect of the invention an indication device for adisc rotatable by drive means, in use, comprises indication means orindication producing means, said means, upon the device being rotated,in use, at or above a predetermined angular velocity, providing anindication that rotation has occurred.

Preferably in said first aspect of the invention an indication devicefor a disc rotatable by drive means, in use, comprises a firstenclosure, indication means in said first enclosure, and a secondenclosure, the indication means being retained in the first enclosureuntil the device is rotated, in use, at or above said predeterminedangular velocity, whereupon there is passage of at, least some of theindication means into the second enclosure and a resultant indicationthat said rotation of the device has occurred, which, indication mostpreferably, is visual, and is visible, or can be viewed, exteriorly ofthe device.

Advantageously the first enclosure is separated from the secondenclosure by separation means, such as membrane means which break(s)when the device rotates, in use, at or above said predetermined angularvelocity. Desirably the device is a transparent circular tube.Conveniently the indication means is a fluid, i.e. a liquid or gas, or asolid, and advantageously is coloured. The device, in use, is applied toa ‘recorded’ disc by an applicator, and may be adhered thereto by meansof a high performance sticker. In another embodiment the indicationmeans is coloured water or other liquid which is held in the firstenclosure by surface tension at an outlet opening. Upon said rotation ofthe device, and thus the creation of a centrifugal force, the liquid is‘pushed’ through the outlet opening into the second enclosure. In astill further embodiment, there is a (different) clear liquid or gas ineach of the enclosures respectively. When said rotation occurs, and theor each separation means breaks or otherwise ceases to retain theliquids or gases in their respective enclosures, the liquids or gasesmix, these being selected so as to produce, on mixing, a colouredcomposition which acts as said visual indication.

According to a second aspect of the invention there is provided a discrotatable by drive means, in use, the disc incorporating indicationmeans, or indication producing means, the indication means or indicationproducing means, upon the disc being rotated, in use, at or above apredetermined angular velocity, providing an indication that rotationhas occurred.

Preferably in a further aspect of the invention there is provided a discrotatable by drive means which incorporates a device according to saidpreferable first aspect of the invention.

Desirably the device is incorporated into the disc or like articleduring its manufacture. The device is embedded in the article thicknessor is sandwiched between the two outer article layers. With thisarrangement a master disc carrying its information could be used toproduce copies by pressing, so that there is no ‘spinning’ which wouldbreak the membrane(s) between the two enclosures. The device isconveniently fitted at the central hole through the disc, but it couldinstead be around the disc outer periphery.

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

FIG. 1 is a schematic plan view of a compact disc in accordance withsaid further aspect of the invention,

FIG. 2 is an enlarged schematic plan view of an indication device of thefirst aspect of the invention,

FIG. 3 is a side view of the device of FIG. 2,

FIGS. 4 and 5 respectively show a disc according to a first alternativeembodiment of the invention, before and after activation of theindication means,

FIG. 6 shows a top view of an indication device of a second alternativeembodiment before being subjected to centrifugal force,

FIG. 7 shows the device of FIG. 6 after being subjected to centrifugalforce,

FIG. 8 shows an indication device as in FIG. 6 but containingphotochromic material, the device being shown before exposure to UVlight,

FIG. 9 shows the device of FIG. 8 after exposure to UV light,

FIG. 10 is a plan view of an optical disc to which is attached askeleton frame carrying the devices of FIGS. 6 and 7, or FIGS. 8 and 9,

FIG. 11 is a plan view of the disc of FIG. 10 after spinning of thedisc,

FIG. 12 is a side view of the disc of FIGS. 10 and 11,

FIG. 13 is a plan view of an optical disc of a third alternativeembodiment with an indication device around its periphery, before thedevice is subjected to centrifugal force,

FIG. 14 is a plan view of the disc of FIG. 13, after it has been spun,

FIG. 15 is a plan view of an optical disc of a fourth alternativeembodiment, incorporating photochromic material, and shown beforeexposure to UV light, and

FIG. 16 is a plan view of a disc of FIG. 15, after its exposure to UVlight.

Although these specific embodiments of the invention disclosed andillustrated herein relate specifically to a compact disc, theapplication does in fact have general applicability to any type ofinformation carrying article, which information is retrieved/read, inuse, by suitable retrieving/reading means when the article is rotated ona suitable drive means, generally at a very high angular velocity. Thusalthough ordinarily the article to which the invention is applied willbe a compact disc or CD ROM which carries information for use in acomputer, or a compact disc on which music, film or speech has beenrecorded, the invention may nevertheless have applicability to othertypes of articles which are rotatable on drive means, and in respect ofwhich it is wished to be able to establish whether or not the articlehas ever been subject to such rotation, for security considerations.

FIG. 1 shows schematically a circular compact disc 10 of any known type,for example containing information for use in operating a computer,containing information which can be read in a computer, or a music/filmCD The disc has a central circular hole 11 therethrough, but in theembodiment shown in FIG. 1, there is a tube 12, which is circular inplan, i.e. toroidal, at the inner extremity of the recorded disc wherethe hole 11 begins. FIGS. 2 and 3 show this tube 12 in enlarged form,and, as will be described herein below, the tube 12 itself isconstructed in accordance with one aspect of the present invention, witha tube incorporated in and forming part of a compact disc, as shown inFIG. 1, being in accordance with a further aspect of the invention. Thetube can have a laterally or radially outwardly extending partsandwiched between layers of the disc or otherwise incorporated into thedisc structure.

The tube 12 is hollow and, in this embodiment, is wholly transparent,being produced, for example, of clear plastics or other suitablematerial. The tube is divided into a first enclosure 13 and a secondenclosure 14 by respective membranes 15,16 defining opposite ends of thefirst enclosure. Although not essential, the degree of arc around whichthe second enclosure extends will generally be much greater than thedegree of arc over which the first enclosure extends around the tube 12,and in the example shown in FIG. 2, the ratio of extent of the twoenclosures is approximately 3:1. The membranes 15,16, can be of anysuitable material/form, provided that, as described below, theybreak/rupture when the tube 12 and/or the disc 10 incorporating the tube12 rotates at or beyond a predetermined angular velocity.

Contained within the enclosure 13 is indication means 17 which can be ofany suitable form, it merely being required that it is visually possibleto detect the presence of the indication means in the second enclosure14 upon rupture/breakage of one or both of the membranes. Althoughnormally the second enclosure 14 would contain only air prior torupture/breakage of the membranes 15,16, this need not be the caseprovided that it could be visually determined when the indication meanspass into this enclosure upon said above-mentioned rotation at or abovepredetermined angular velocity.

Preferably the indication means is a low viscosity liquid which isdesirably coloured so that its passage into the second enclosure 14 willbe easily visible exteriorly of the device and also of the disc to whichthe device is fitted. However in other embodiments the liquid need notbe of low viscosity, and instead of a liquid, a gaseous fluid,preferably of low viscosity, and/or preferably coloured, could be usedin the enclosure 13. Moreover the indication means could instead be asolid, for example particulate material, and in a yet further example,the indication means could be any combination of the examples quoted asindication means. Preferably the membranes are in the form of thinbreakable plastic films or sheets, which although designed tofracture/break/rupture at a predetermined angular velocity, aresufficiently strong to allow transportation of the tube itself, or thetube fitted to a compact disc. In other words normal transportationimpacts can be absorbed leaving the membranes undamaged.

However the membranes are designed and/or are of a material which willassuredly fracture/rupture/break when the device is subjected to theabove-mentioned predetermined angular velocity, this being, for example,the typical speed at which a compact disc drive operates with knowncomputer equipment, CD players and the like. However the membranes canbe produced so as to fracture/rupture/break at any desired speed, itmerely being necessary to ensure that the indication means enter thesecond enclosure 14 even if the device/disc has been run momentarily ona disc drive or equivalent. At said predetermined angular velocity,there is a certain centrifugal force applied to the indication means 17in the enclosure 13, and this force, in conjunction with the design ofthe membranes, ensures that when the membranes rupture/break/fracture,the indication means passes into the second enclosure 14 so that, in theembodiment described, the indication means then fills the whole of theinterior of the tube 12, thus producing an exteriorly visible ring ofcolour or equivalent visual indication means. Subsequently anyonelooking at said tube can tell that it had been subject to rotation, sothat an associated disc could have been read, i.e. the contents hadretrieved at least once. The tube thus in this case acts as a securitydevice to alert, for example, the recipient of the compact disc thatinformation intended to be sent on a secure basis by the sender of theCD had been subject to a security breach during transit.

It will be appreciated that as far as the visible indication isconcerned, it is merely necessary that someone checking the security isable to establish a change in the appearance of a particular area of thedevice, for example a change from a clear empty area before rotationcontrasted with the presence of indication means in said area afterrotation. Accordingly it will be appreciated that the whole of thedevice need not be visible at all, and in particular the first enclosure13 could be concealed from view at all times, it merely being necessarythat the second enclosure 14, or at least a part thereof is alwaysvisible, or can be visually inspected, to allow the contrast referred toabove to be detected so as to enable it to be determined that themembrane or membranes separating the part of the device containing theindication means from the exteriorly visible part of the device has orhave been ruptured by rotation. If required, the visible part of theenclosure 14 could have a cover which can be opened to check whether thedevice/disc has ever been rotated. Although not as convenient, it willbe appreciated that the device could be provided in forms other thanthat of a circular tube, although this is most convenient for utilizingthe centrifugal force referred to above.

In the embodiment shown in FIG. 1, the tubular device 12 is incorporatedinto the disc itself. The associated process is thus suitable for massproduction of factory recorded discs, with there being no ‘spin’ orrotation in the production method which would break the membranes.Accordingly with this mass production arrangement, the tube 12 could beembedded in the body of the disc around the central hole 11 as shown, oralternatively it could be sandwiched between, for example, the two outerlayers of the disc during the production process. If deemed necessary, a‘master’ disc could include the indication device, i.e. if one or more‘master’ discs can be recorded using a ‘no spin’ method, recordable CDswhich already incorporate the indication device could be used. Massproduced discs can then be copied from the master in the normal way bypressing or equivalent, this being in a ‘no spin’ manner so that themembranes would remain intact. Thus this aspect of the invention relatesto a disc or the like article rotatable by drive means, in use,incorporating an indication device by means of which apurchaser/recipient can easily tell whether the article has ever beendriven on a disc drive, i.e. whether the information on the disc couldhave been read/retrieved.

Another aspect of the invention relates to the device, per se, forexample as shown in the embodiment of FIGS. 2 and 3. This isparticularly applicable for use with a disc or the like articlerotatable by drive means, in use, where there is individual utilizationwhich involves a ‘spin’ or rotation method of writing/recording theinformation onto the disc or like article by the user/sender. In oneembodiment of this arrangement, the indication device would be suppliedas a self contained unit, in conjunction with a high performancesticker, which could be used to apply the tube 12 to the disc or likearticle once it has been ‘recorded’ upon using a ‘spinning’/rotationmethod of writing, e.g. by the use of a compact disc recorder. Thus oncethe rotation of the disc has been completed, the tube 12 or other formof indication device is then applied to the disc by means of a suitablepress-like applicator which can be part of the self contained unit,this, for example, sticking the device in position at the centre of thedisc so as to form a similar arrangement to the mass produced disc ofFIG. 1. By accurately lining up the CD relative to the indicationdevice, perfect balance of the processed CD with indication means(essential for proper running on the drive) would be achieved. Howeverany other appropriate method of fixing the indication device to the‘pre-recorded’ disc can be used.

Accordingly it will be appreciated that the invention relates not onlyto a disc or like article incorporating ‘therein’ an indication deviceof the invention, but also to such an indication device per se forafter-fitting. It will be appreciated that the article to which theindication device is fitted or into which it is incorporated can be ofany shape, and moreover can be of any form, typically a CD-ROM, a musicCD, a DVD compact disc or even a now generally obsolete vinyl disc ofsingle, EP or LP form.

In one alternative embodiment, the device is in the form of a centralcircular tube constituting a hub about which the device is rotated on adisc drive spindle. Emanating radially outwardly from the hub are anumber of spokes equi-angularly spaced around the hub, the spokes beingstraight tubes forming second enclosures separated from the firstenclosure, namely the hub, by any suitable separation means, includingthose described hereinbefore. Prior to a first rotation the indicationmeans is retained in the hub. Rotation causes the indication means to besubjected to centrifugal force and to enter the spokes, and preferablyreach the respective ends thereof at the inner circular periphery of thedisc to which the device is fitted in use or manufacture. It may bepossible to select indication means such that graduations along one ormore spokes show the amount of use of the disc, i.e. how far along thespoke the indication means has reached. If necessary, some means ofallowing trapped air at the ends of the spokes to escape could beprovided, so as not to prevent movement of the indication means. Theindication means could be pressurised in such a way that would send themeans all the way along each spoke, whilst not causing actuation duringdisc transportation.

In another alternative embodiment, there is separation means between afirst enclosure and a second enclosure, which separation means includesor is wholly constituted by an outlet opening. Water, preferablycoloured, is ordinarily held in the first enclosure by surface tensionat the outlet opening, which could be specially designed to facilitatesuch retention. However on rotation of the device/disc, the surfacetension is overcome by the water being ‘pushed’ through the outletopening into the second enclosure where it acts as a visual indicationthat rotation has taken place. A suitable alternative liquid to watercould of course be used instead.

In a still further alternative embodiment, there is a different clearliquid or gas in two separated enclosures respectively. When rotationoccurs and the or each separation means breaks or otherwise ceases toretain the indication means, i.e. the clear liquids or clear gases, intheir respective enclosures, the liquids or gases mix. The liquids orgases are selected so that the mixing produces a coloured compositionwhich acts as said visual indication of the rotation having taken place.Accordingly it will be appreciated that as used herein the term‘indication means’ includes solids, liquids and gases which are alwaysvisible, e.g. coloured, and also a solid, liquid or gas which normallyis clear, but which when combined with a (different) solid, liquid orgas produces a visible resultant composition which provides said visualindication. Moreover in all embodiments the visual indication could be acolour change, and thus various combinations are possible, i.e. liquidand gas, liquid and solid, gas and solid, with the possibility of atleast one of these combination indication means normally beingnon-clear.

In a yet still further alternative embodiment, use is made of a smallelectrical charge which may possibly be generated by way of frictionwhen the CD is rotated on the drive means. Accordingly some kind ofconductant display method could be utilized to provide a visualindication that the disc has been rotated. The indication device neednot be circular, i.e it could be of any shape or size, such as a smallpatch on one side of the CD. Alternatively it could be disposed on theouter perimeter/periphery of the disc where most friction would beexperienced. A counterbalance would be employed, e.g. at the exactlyopposite side/edges to ensure the disc is balanced for proper rotationin the disc drive. In a still another embodiment, heat generated by theabove mentioned friction is utilized to produce a visual indication ofrotation having taken place. The indication means or the indicationproducing means in these cases can be considered to be the means whichgenerate the friction, i.e. the means that ‘provide’ an indication(charge or heat) that rotation has occurred.

Although in most instances the indication that the ‘disc’ has beenrotated will be a visual one, it could be that in some instances theindication is audible and/or tactile, with or without being visual. Herethe indication means or indication producing means of the indicationdevice could be considered to be the means which generate theaudible/tactile affect.

In one variation, there is provided a ‘mechanical’ indication device. Avery thin disc/plate of metal or other material is suspended in an innerenclosure in the protected article, e.g. a CD. The suspension mediumcould be air or a liquid/gel. The disc/plate is fixed to a pivot aroundwhich it can spin (angularly rotate). When the CD is received on itsdrive means, the disc/plate spins. The pivot can be of a screw type, sothat the disc/plate will travel up or down the screw, and ‘jam’ intoplace at a predetermined position (destination). The dimensions of thesecomponents could be thinner than wafer-thin. Once the disc/plate is‘jammed’ in place, it provides a visual indication that the CD has beenspun. It could do this, for example, by smearing a minute amount ofsuitable indication means, such as the suspension means, onto thetransparent inner surface of its case.

In a second variation, shown in FIGS. 4 and 5, at least one LiquidCrystal Display (LCD) 18 is used. In the illustrated embodiment, it isin the form of an annulus, spaced from, but concentrically around, thecentral hole in the disc 19. The LCD could be of a type which, onceactivated, remains activated, in the same way that photographic filmremains imprinted with light. The activation of the LCD could betriggered by heat or electricity generated by the spinning of thearticle, e.g. a CD, incorporating the LCD, or by laser light from thearticle reader whilst the disc is spun. FIGS. 4 and 5 respectively showthe LCD deactivated and activated, the activated LCD being indicated bynumeral 18 a. Alternatively, the LCD could merely be an area on the bodyof the disc, for example, a triangular area.

In a third variation, indication means in the form of laser lightreactive material (possibly organic/biological) could be included as aningredient of the plastics/silicone or other mixture from which thearticle, e.g. a CD, is manufactured. Alternatively the laser lightreactive material could be in the form of a (thin) plate/disc or thelike which is incorporated into the CD itself. Once the ‘reading’ of theCD commences, in use, i.e. once the laser light of the reading devicestrikes the material, its appearance would change in a clearly visiblemanner. The ‘signaling’ effected by the change could be a change ofcolour and/or change of texture, or the like. Alternatively the ‘signal’could be audible and/or tactile, with or without being visual.

A further embodiment relates to the use with all variations of the‘alert’ indication device of the invention of photochromic material toprovide means of verifying whether a disc or like article is genuine.

The photochromic material changes state under exposure to suitable light(electromagnetic radiation of a certain wavelength), the changeremaining for a time after removal of said light. In this manner amanufacturer or supplier can use photochromic (photochemical) materialwhich when subjected to non-visible light, e.g. ultraviolet light,changes to a different colour, or different shade, or displays anidentifying or other logo, or writing or a picture, each of which can beunique to the manufacturer or supplier, thus showing that the article,e.g. an optical disc, is genuine, i.e. an original and not a(counterfeit) copy. The photochromic material can be one compound of thematerial from which the article, e.g. a CD, is manufactured, e.g. mixedwith the polycarbonate substrate compound. Alternatively thephotochromic material can be secured to the disc, e.g. by adhesive or bybeing embedded into its surface, or be sprayed onto part of the disc,e.g. in the same manner as printing on the disc surface.

FIGS. 6 to 9 show an indication device in the form of a flat tube 110,made of glass, plastics or other transparent material. The flatteningincreases visibility from above. Typically the tube (device housing) isvery small, for example with a length of 4 cm, a width of 3 mm, and adepth of 1 mm. Whilst the respective side walls and end walls of thetube may be of the same constant thickness, the upper and lower wallthicknesses can be less.

FIG. 6 shows a gel (in this embodiment a silica oil gel) 111 in thesealed tube 110, which acts, in use, as indication means in the samemanner as previously described. The gel is in the end part of the tube(the alert area) disposed, in use, nearest the disc centre, whilst theremainder of the tube shown in FIG. 6 merely contains air, with amembrane 112 effectively being formed between the gel and the air,although said membrane is due to the surface tension of the gel'sviscosity and need not be a separate structural dividing member.However, this could be provided if required. Preferably, the geloccupies a significant area of the inside of the tube. With a circulardisc, for example a CD or other optical disc, two tubes 110 are securedto the upper surface of the disc along a diameter of the disc atrespective opposite sides of its centre. It will be understood thatalthough a single tube would suffice, a pair of tubes is preferred tomaintain the balance of the disc during rotation. As described, rotationof the disc at or above a predetermined angular velocity will cause thegel to travel up along the tube as a result of the centrifugal forcegenerated by the disc rotation. This causes a mixing of the gel withinthe whole tube, and thus clearly shows that the disc has been used, i.e.rotated. Someone checking the security of the disc is thus clearly ableto establish, by looking at the nature of the gel in the tube, that thedisc has been used at least once. Alternatively, in the preferredembodiment, instead of a spreading of the gel within the whole of thetube, the gel 111 or other indication means could merely (bodily)transfer into the originally empty area (the alert area), so that thearea which originally contained the gel then becomes empty. This is theembodiment shown in FIGS. 6 and 7, where upon rotation of the disc, thegel bodily transfers to the opposite end of the tube, as shown in FIG.7.

One particular form of gel 111 can contain photochromic material, i.e.material which changes colour or shade, or other characteristic,reversibly, in light of a particular frequency or intensity. Inparticular the photochromic material mixed with the gel in the straighttube 110 of FIGS. 6 and 7 can display its normal characteristic in whitelight, i.e. normal visible light, whilst displaying a differentcharacteristic after being subjected to ultraviolet light. Theultraviolet light can be provided at any convenient apparatus, forexample a conventional bank note checker, a hand-held device or abarcode scanner. The material can be tailored to the requirement of themanufacturer or supplier so as to provide a distinctive, individual,indisputable ‘signature’ to indicate the origin of the disc, i.e.manufacturer or supplier. The photochromic material can be such thatunder after exposure to UV light it merely changes colour or shade, ordisplays a logo, wording or a picture, the logo, wording and pictureaspects being more applicable to when the photochromic material is usedin the manufacture of the disc, as will be described in relation toFIGS. 15 and 16. The end user of the optical disc will receiveinformation as to the correct colour etc., to which the photochromicindicator will change.

The only difference between the tube 110 a of FIGS. 8 and 9, and thetube 110 shown in FIGS. 6 and 7, is that the gel 113 in the tube 110 acontains the specific photochromic material. Accordingly afterultraviolet light is shone on the tube 110 a of FIG. 8, the appearancewill change to that shown in FIG. 9, i.e. the gel will change colour. Ifthe particular colour is known to be associated with a particularmanufacturer or supplier, then this will verify that the disc isgenuine. Clearly the exposure to UV light can occur before or after thetube has been subjected to centrifugal force, i.e. when the tube is asin FIG. 6 or as in FIG. 7.

Accordingly it will be appreciated that with this arrangement there isprovided not only an indication device to establish whether or not adisc has been used, but also a verification device to establish whetherthe disc originates from an authorised manufacturer/supplier. The effectwill effectively be ‘switched’ in that once the ultraviolet light hasbeen removed the genuine unique colour or shade will, in time, in normallight, fade back to its original state shown in FIG. 8 until once againthe tube is exposed to ultraviolet light. Alternatively, a ‘blast’ ofwhite light can be provided to return the photochromic material to itsoriginal state. Thus the change from exposure to one type of light toanother can effect this switching. In FIGS. 8 and 9, the gel isindicated by the numeral 113 in its normal form, i.e. when in ordinarydaylight, and by the numeral 113 a in its switched form, i.e. afterbeing subjected to ultraviolet light. The switching can be carried outan unlimited number of tines. In one embodiment it may be that thematerial thermally fades back to its ‘white light’ state.

FIGS. 10 to 12 show a (skeleton) chassis or frame 114 used for affixinga pair of the tubes 110 (or 110 a) to a disc 115 instead of merelyaffixing each tube individually. The frame 114, which can be a thinplastics material sheet, can have a central circular portion 116 to bereceived in a correspondingly sized central recess in the disc 115.Extending radially from the portion 116 in respective aligned oppositedirections therefrom are arms 117, 118 which are of a length and widthto accommodate a flat tube 110, the tubes being shown respectively inposition on the two arms. As can be seen from FIG. 12, the arms areextremely thin, for example having the same depth as a tube 110. Theframe can be in the form of a high performance sticker so that backingmaterial can, in a known manner, be peeled off both sides of the frameso that the undersides of the arms can be adhesively secured to theupper surface of the disc 115 to hold the frame to the disc, adhesivesecurement also being possible at the central circular portion 116 ofthe frame 114 with the disc. In a preferred embodiment the uppersurfaces of the arms are similarly formed with adhesive which is exposedwhen backing material is peeled therefrom, and this allows the tubes 110to be secured in place on the arms by means of said adhesive. However,it is not essential that both sides of the frame are formed with suchadhesive and backing, and it may be that this applies in most instancesonly to the underside for its securement to the disc, some other form ofsecurement being employed to secure the tubes to the upper surfaces ofthe arms. The nature of the adhesive used to secure the frame to thedisc 115 will usually be such so as to make separation of the frame fromthe disc 115 impossible without irreversibly damaging the disc. FIG. 10shows the disc before it has been spun, whilst FIG. 11 shows it afterspinning, with the gel 111 now moved bodily along its associated tube,as in FIG. 7.

FIGS. 13 and 14 show a disc 119 to which it is secured an indicationdevice in the form of a circular glass tube 120 in a similar way toFIGS. 1 to 3. However here the tube 120 is around the outer periphery ofthe disc. Moreover the arrangement shown in FIGS. 13 and 14 differs inthat the tube contains a gel 121 with the ‘membranes’ 122 at theopposite ends respectively of the gel being formed solely by the factthat there is a surface tension effect due to the gel's viscosity whichunder normal conditions retains the gel in place. For example if thedisc is dropped or mis-handled during transportation there is nospreading of the gel, i.e. breaking of said membranes. If however thedisc 119 is rotated at or above a predetermined angular velocity, thenthe membranes 122 are ‘broken’ and the gel spreads around the tube toprovide a visual indication that the disc has been used. Although it ispossible to use either straight tubes or circular (annular) tubes tocontain the visual indication means, it may be that a straight tube,either alone, or in pairs as shown in FIGS. 10 and 11, is moreacceptable, in that with a circular tube at the centre of the disc thecentrifugal force may in some instances be insufficient to effectbreaking of the membranes. However it is believed that a circular tubewould be acceptable if used around the outer periphery of the disc wherethe centrifugal force would be greater. Of course, any shape of tube isacceptable, providing it can be arranged on the disc so that themembranes are broken on rotation above the predetermined angularvelocity. The tube can be stained by the gel as it passes along/aroundit. The volume 123 which initially does not contain the gel, could beempty (contain only air) or contain a liquid, gas or solid to mix withthe gel.

FIGS. 15 and 16 show an optical disc 124, for example a CD, which ismade wholly or partly of photochromic material, e.g. that referred to inrelation to the gel of FIGS. 3 and 4, so that the disc itself isresponsive to a change from white to ultraviolet light in the samemanner as described for the gel in FIGS. 3 and 4. Although not shown,the disc 124 would include indication means, e.g. it would have one ormore tubes 110, or even 110 a, attached to its surface. In oneembodiment, the photochromic material is applied to the surface of thedisc under a protective lacquer coating. One example of suitablephotochromic material is Photosol (RTM), manufactured and sold by PPGIndustries, Inc. of Pittsburgh, U.S.A.

With FIG. 16, the disc is shown after having been subjected toultraviolet light, (whether or not it has been rotated), and it can beseen that previously invisible wording 125 formed by the photochromicmaterial is now visible. Alternatively or additionally, the colour orshade of the disc could change due to the presence of the photochromicmaterial. If the wording, logo, colour etc is identified as originatingfrom the manufacturer or supplier of the disc or otherwise verifies thedisc, then by using both the indication means and the photochromicmaterial, it can be seen that the CD is not only brand new but is alsogenuine. The colour change or the appearance of the wording or logo maytake approximately one minute to occur, although this may vary dependingupon the intensity of the ultraviolet light to which the disc issubjected. Once the UV light source is removed, the wording, logo or thegenuine unique colour will begin to fade. In other words the disc willswitch back to its original normal colour in daylight, with this fadingof the genuine unique colour, wording etc occurring over a period oftime, the disc then remaining as shown in FIG. 15, until it is againexposed to UV light. Of course once the indication means of the dischave been ‘triggered’, such means will never return to the ‘brand new’state shown for the tubes 110 in FIG. 10 where the gel is at the ‘inner’end of each tube.

Thus with the disc shown in FIGS. 15 and 16, it will be appreciated thatit would be possible to tailor the photochromic material so that whenultraviolet light is shown on to it there is disclosed a logo, wordingor picture identifying, for example, the manufacturer and/or supplier ofthe disc, to indicate that if this is visible then the disc is genuineand, conversely, that if it is not then the disc is a counterfeit, copyor fake. Of course the photochromic material can be of any colour,shade, appearance etc before actuation, the important quality being itschange upon actuation.

It will be appreciated that although the ‘tailored’ photochromicmaterial has been described in two alternative forms, namely within thegel or forming the whole or part of the material of the disc, it wouldbe possible merely to affix a lesser or greater patch of suchphotochromic material to the disc or to a tube, or to spray photochromicmaterial thereon. Alternatively the photochromic material could be mixedwith the polycarbonate substrate compound before it is formed into thedisc, it being appreciated that it is merely necessary to provide atleast a small amount of a photochromic material somewhere in or on thedisc, including in or on the security/indication means, so that once UVor other non-white light to which the photochromic material issensitive, is shone onto the disc, the photochromic material changesappearance, as described to indicate/verify whether or not the disc isgenuine. As mentioned above, it would of course be possible to providephotochromic material which is sensitive, i.e. switches its appearance,in response to light of a different frequency/wavelength from that ofultra violet light, (e.g. laser light), although ultraviolet light is tobe preferred, in view of its present common availability as described inbank note testing devices and the like.

To apply indication devices to an optical disc, the production processof the disc need not be changed, but rather a final process can be addedwhere the device is simply applied by a robotic arm. It can be appliedusing heat to fuse the device to the disc, or glued on, or applied usinga high performance sticker as previously described. It may be that thedevice is embedded into the disc's surface by digging or carving out achannel or gutter on the top of the disc and then pressing the deviceinto it making permanent the application/incorporation. This isparticularly convenient where the photochromic material is applied inthe form of a patch. In situations where discs are produced bysandwiching two halves together, e.g. DVD's, the device can be installedbetween the two outer layers before they are joined. If necessary,channels can be dug or carved on the inner side of each disc platebefore they are joined, to accommodate the device. In some instances anindividual purchases can apply the device to a disc.

Although the membranes in the tubes have been described as being formedby the surface layer of the gel, alternatively the division between thegel and the air in the tube could be by way of a specific gel plug, or aplug of any other material and of any other shape. In one alternativethe indication means, such as a gel, can be held in place by any type oftemporary blocking barrier/one-way door mechanism.

Accordingly. Total protection can be provided particularly, but notexclusively, for users of business software who may unwittingly useillegal unlicensed (counterfeit) business software and are thus liableto prosecution and fines.

In a still further embodiment, the entire indication/security device isno thicker than two or three sheets of paper. Rather than the glass orplastic tubing mentioned above, the device housing is actually a thinplastic sheeting, designed to accommodate the indication meanscomfortably inside it. The principles here are exactly as those of thepreferred device specifications above. This envisaged version does notlook dissimilar to the patented battery/cell power level tester devicesupplied with the square 9V batteries, and manufactured by Duracell andsold under Trade Mark COPPER TOP™ TESTER.

As described, the photochromic material changes its state after exposureto UV light, with its change back not being instantaneous, i.e. thechange remaining for a time after the UV light has been removed. This isquite different from the arrangement used with currency note checking,where photochromic material is not used. However the verification of thedisc could be by way of this bank note checking technique, i.e. using‘invisible ink’ which only registers, and does not change state, whilstsubjected to UV light. This would be, like the use of photochromicmaterial, in conjunction with the use of indication means to denote thedisc has been spun.

A further aspect relates to PC's which have CD reading and writingabilities, e.g. which have means which are capable of reading a CDwhilst at the same time writing onto it. The indication device would beadapted to take account of this CD read and write facility as follows.The first time a CD is used, the (laser) writer would write onto the CD.The next time the CD is used, an onscreen display would indicate thatthe CD had been read once. In fact it will be possible to conveydetailed information such as how many times accessed, by whom, which PCetc.

As general non-exclusive specifications, as appropriate, for all theinventive aspects in this application, the following is to be noted:

-   -   i) Devices and/or their components and their effects can be any        material (solid/liquid/gas/plasma), shape, style, colour, shade        of colour, transparent/clear. Any alert indications may be in        the form of text, image, logo, picture etc.    -   ii) Devices may be triggered/actuated and/or powered/driven by        centrifugal force, heat, magnetic force, electricity, laser        light, UV light, light of any or all other kinds, solar power,        human touch or some other external or internal force.    -   iii) Each of the security devices can be added/incorporated at        the article's point of manufacture, or applied by an individual        to a single article.

1. A readable disc, in use rotatable by drive means, having indicationmeans or indication producing means that provide an indication thatrotation has occurred when the disc in use is first rotated at or abovea predetermined angular velocity characterized in that the indicationmeans or the indication producing means provide said indication thatrotation has occurred without affecting reading of the disc during saidfirst or any subsequent rotation of the disc.
 2. A disc as claimed inclaim 1, comprising a first enclosure, indication means or indicationproducing means in said first enclosure, and a second enclosure, saidindication means or indication producing means being retained in thefirst enclosure until the disc is rotated, in use, at or above saidpredetermined angular velocity, whereupon there is passage of at leastsome of the indication means or indication producing means into thesecond enclosure and a resultant indication that rotation of the dischas occurred.
 3. A disc as claimed in claim 2, wherein the resultantindication is visual.
 4. A disc as claimed in claim 3, wherein saidresultant indication can be viewed exteriorly of the disc, in use.
 5. Adisc as claimed in claim 2, wherein the first enclosure is separatedfrom the second enclosure by breakable membrane means.
 6. A disc asclaimed in claim 2, wherein the indication means or indication producingmeans is a fluid.
 7. A disc as claimed in claim 6, wherein theindication means or the indication producing means is a liquid.
 8. Adisc as claimed in claim 7, wherein the liquid is coloured.
 9. A disc asclaimed in claim 7, wherein said liquid in said first enclosure isclear, and said second enclosure contains further clear liquid, saidliquids in said first and second enclosure respectively mixing upon saidrotation of the disc, in use, at or above said predetermined angularvelocity to provide a coloured visual indication of rotation havingoccurred.
 10. A disc as claimed in claim 7, wherein the liquid is heldin said first enclosure by surface tension at an outlet openingtherefrom.
 11. A disc as claimed in claim 1, wherein said indicationmeans or said indication producing means is in the form of a tube havingat least part thereof transparent.
 12. A disc as claimed in claim 11,wherein the tube is circular in plan.
 13. A disc as claimed in claim 12,wherein the circular tube is wholly transparent.
 14. A disc as claimedin claim 11, wherein the tube comprises a circular hub from which atleast one radial arm extends.
 15. A disc as claimed in claim 14, whereinthe hub and the at least one radial arm respectively constitute firstand second enclosures, the first enclosure containing indication meansor indication producing means.
 16. A disc as claimed in claim 11,wherein the tube is straight.
 17. A disc as claimed in claim 16, whereinthe tube is flat.
 18. A disc as claimed in claim 16, wherein the tube iswholly transparent.
 19. A disc as claimed in claim 16, wherein theindication means or indication producing means is a gel.
 20. A disc asclaimed in claim 19, wherein the gel is held in said tube or a firstenclosure of said tube by a membrane formed by the surface tension ofthe gel's viscosity.
 21. A disc as claimed in claim 19, wherein the gelis arranged so that, in use, upon rotation of said disc it transfersbodily into said tube or a second enclosure of said tube.
 22. A disc asclaimed in claim 1, wherein the indication means or indication producingmeans is held in a first enclosure which is separated from a secondenclosure, into which at least part of the indication means orindication producing means moves, in use, upon said rotation, by barriermeans.
 23. A disc as claimed in claim 22, wherein the baffler means arebreakable films/sheets.
 24. A disc as claimed in claim 1, wherein, inuse, upon said rotation, the indication producing means produces africtionally generated electrical charge which is utilized to providesaid indication.
 25. A disc as claimed in claim 24, wherein saidindication is a conductant display.
 26. A disc as claimed in claim 1,wherein, in use, upon said rotation, the indication producing meansproduces frictionally generated heat which is utilized to provide saidindication.
 27. A disc as claimed in claim 1, in which said indicationthat rotation has occurred is audible.
 28. A disc as claimed in claim 1,in which said indication that rotation has occurred is tactile.
 29. Adisc as claimed in claim 1, in which said indication means or indicationproducing means is in the form of thin plastics material sheeting.
 30. Adisc as claimed in claim 1, including/incorporating photochromicmaterial.
 31. A disc as claimed in claim 30, wherein the indicationmeans or indication producing means contains photochromic material. 32.A disc as claimed in claim 31, wherein the photochromic material ismixed with a gel.
 33. A disc as claimed in claim 31, wherein thephotochromic material changes its state, in use, when exposed toultraviolet light.
 34. A disc as claimed in claim 1, including a thinplate/disc on a screw-type pivot, which, in use, upon rotation of thedisc, travels along the pivot to jam in a position which provides saidindication.
 35. A disc as claimed in claim 34, wherein said plate/discis suspended in a suspension medium.
 36. A disc as claimed in claim 34,wherein in said jammed position, in use, said plate/disc has smearedindication means to a surface of a case of the indication means orindication producing means.
 37. A disc as claimed in claim 1, comprisinga liquid crystal display which is activated, in use, by rotation of saiddisc.
 38. A disc as claimed in claim 37, wherein the activation is byheat or electricity generated by the rotation of said disc, in use. 39.A disc as claimed in claim 37, wherein the activation is by laser lightfrom a reader of the disc.
 40. A disc as claimed in claim 12, whereinthe tube is secured in a central circular opening through the disc. 41.A disc as claimed in claim 40, wherein the indication means orindication producing means is embedded in the body of the disc.
 42. Adisc as claimed in claim 41, wherein the indication means or indicationproducing means is embedded around a central hole of the disc.
 43. Adisc as claimed in claim 1, wherein the indication means or indicationproducing means is sandwiched between two layers of the disc.
 44. A discas claimed in claim 1, having at its periphery indication producingmeans which, when the disc is rotated, in use, produce a frictionallygenerated electrical charge which is utilized to provide saidindication.
 45. A disc as claimed in claim 44, wherein a counterbalanceis provided to said indication device disc, to balance the disc uponrotation, in use.
 46. A disc as claimed in claim 1, having a framesecured to one side thereof and carrying a pair of said indication meansor indication producing means.
 47. A disc as claimed in claim 46,wherein the frame is adhesively secured to the disc and the indicationmeans or indication producing means are adhesively secured to the frame.48. A disc as claimed in claim 46, wherein the frame has a centralcircular portion received in a central hole of the disc and at least twoarms extending radially from said central portion, said armsrespectively carrying said indication means in the form of tubes.
 49. Adisc claimed in claim 48, wherein the frame is formed of a thin plasticsmaterial sheet.
 50. A disc as claimed in claim 1, wherein the indicationmeans or indication producing means is disposed continuously around theouter periphery of the disc.
 51. A disc as claimed in claim 1, which hasphotochromic material on a surface thereof.
 52. A disc as claimed inclaim 51, wherein the photochromic material is applied to the discsurface under a protective lacquer coating.
 53. A disc as claimed inclaim 52, wherein a change of state of the photochromic material, inuse, renders wording and/or a logo visible.
 54. A disc as claimed inclaim 1, in the form of a CD for use with a computer having both areading and writing ability.